November 13, 2013

From a NASA spacecraft Mars today looks like a dead, rusted hulk of a world . But, billions of years ago when the planets of our solar system were still young, it was a very different world. Liquid water flowed in long rivers that emptied into lakes and shallow seas. A thick atmosphere of CO2, a potent greenhouse gas, blanketed the planet and kept it warm. In this cozy environment, living microbes might have found a home, starting Mars down the path toward becoming a second life-filled planet next door to our own.

The high-resolution image at the top of the page shows the planet's oldest terrain is rich in clay minerals, which formed in liquid water. Ancient rivers carried clays (green) into a lake that once filled Mar's Jezero crater.

The only way Mars could have been wet and warm 4 billion years ago, is if it also had a thick atmosphere. A thick blanket of CO2 and other greenhouse gases would have provided the warmer temperatures and greater atmospheric pressure required to keep liquid water from freezing solid or boiling away.

Something caused Mars to lose that blanket. One possibility is the solar wind. Unlike Earth, Mars is not protected by a global magnetic field. Instead, it has “magnetic umbrellas” scattered around the planet that shelter only part of the atmosphere. Erosion of exposed areas by solar wind might have slowly stripped the atmosphere away over billions of years. Recent measurements of isotopes in the Martian atmosphere by Mars rover Curiosity support this idea: light isotopes of hydrogen and argon are depleted compared to their heavier counterparts, suggesting that they have floated away into space.

Scientists have also speculated that the planet's surface might have absorbed the CO2 and locked it up in minerals such as carbonate. However, this theory has faded in recent years as Mars rovers and orbiters have failed to find enough carbonate to account for the missing gas.

The upcoming MAVEN mission will be the first mission to Mars specifically designed to help scientists understand the ongoing escape of CO2 and other gases into space. The probe will orbit Mars for at least one Earth-year. At the elliptical orbit's low point, MAVEN will be 125 km above the surface; its high point will take it more than 6000 km out into space. MAVEN's instruments will track ions and molecules in this broad cross-section of the Martian atmosphere, thoroughly documenting the flow of CO2 and other molecules into space for the first time.

Once Jakosky and his colleagues know how quickly Mars is losing CO2 right now, they can extrapolate backward in time to estimate the total amount lost during the last four billion years. "MAVEN will determine if loss to space was the most important player in driving Martian climate change," Jakosky says.

In the grand scheme of the Solar System, Earth orbits alongside a world that began with as much promise for life as our own … yet turned out so differently. After all these years, MAVEN could write the final chapter in a haunting planetary mystery.

Comments

A theory of past and future states of climate throughout the solar system needs to incorporate a holistic approach and a good place to start is the work of Milutin Milankovic. It is likely that the earths geologic time scale has markers that will corespondent to in some way to mars and other planetary bodies as well. I look forward to the day when this becomes common knowledge and we can begin to protect ourselves from what is forecastable.
Ice core samples from Greenland and Antarctica show a time lag of approximately 600 years from the time warming occurred and when CO2 levels in the atmosphere increased. Climate change is a result of cosmic forcing, period.

Lee...You also have to take into account the heat given off by all of our activities...not just the emissions from our engines. They call it the internal combustion engine...it gives off a lot of heat...hence the need for a radiator. In the past there were just the natural processes of the world.
Think also of all the extra reflectivity of our cities kicking all that extra heat into the atmosphere. We have had a huge negative impact on this planet's climate....and we shall reap our rewards in spades.....try to have a slightly more open mind.

@John
Yes the earth has warm cities and combustion engines. but what does that have to do with the CO2 time lag paradox. I bet you live in a house and drive a car. It is foolish to use the combustion of fossil fuels to drive our civilization when we have access to much higher energy densities. If it is possible to farm on Greenland like the Vikings did 1000 years ago, will we still be so willing to collapse our economies and starve our populations to death? Global warming is a good thing and it is the cooling that is the nemeses; the Milankovic cycles and the ice ages are a testament to this. Open your mind friend, to something outside your little box and short life span. Maybe then you can admit the truth that man is a product of nature and by that definition so are his inventions.

There is clear evidence of water flow on the surface of Mars when looking at satellite and ground images. This is seen due to river beds and gullies being present on the surface which are clear indicators of flowing water. The sediments of that near these features are also of this nature, giving further evidence to the existence. I believe that the planet once had water occupying it, however it has now dried up due to the drastic climatic change.

The evidence for water is clear, with many landmarks showing this. People who do not believe this need to look at the geomorphological features and realize that the reality is that water once flowed on this planet. Deltas, river beds and other features have being found, giving full evidence to the existence of this.

I can see your point John however i believe this can not be fully proven until full investigation is done around the subject. These features could be of some other unknown origin and we are just comparing them with something we know well to try and give an explanation for them.

What may have happened is Mars is much smaller than Earth and so cooled down quicker. It's volcanism stopped so that means it solidified internally. Once it's core stopped it no longer produced a magnetic field to shield it from the solar wind. Mars is quite far from the sun so it's solar wind may be less than that which buffets Earth but Mars is also smaller so it could not hold onto it's atmosphere gravitationally. With no magnetic field to protect it and a weak gravitational pull the sun would erode Mars' atmosphere quite quickly. Apparently CO2 is still being produced, but when that stops Mars will be just another barren rock.